This study reports a novel electrocatalytic method for the reduction of uranyl ions (U(VI)) to uranium(IV) solids using a catalyst composed of atomically dispersed gallium on hollow nitrogen-doped carbon capsules (Ga-Nₓ-C). The method relies on the presence of secondary metal ions, such as alkaline earth metals, transition metals, lanthanide metals, and actinide metals, which promote the formation of UO₂ or bimetallic U(IV)-containing oxides through a two-electron transfer process. The absence of U(IV) solid products was observed in the presence of alkali metal ions. Mechanistic studies revealed that strong binding affinities between U(IV) and certain secondary metal ions suppress the re-oxidation of U(IV) to U(VI), leading to the generation of U(IV)O₂ and MₓU(IV)O₂. This work provides fundamental insights into the electrochemical behavior of uranium in aqueous media and offers a promising approach for uranium capture from nuclear waste and contaminated water.This study reports a novel electrocatalytic method for the reduction of uranyl ions (U(VI)) to uranium(IV) solids using a catalyst composed of atomically dispersed gallium on hollow nitrogen-doped carbon capsules (Ga-Nₓ-C). The method relies on the presence of secondary metal ions, such as alkaline earth metals, transition metals, lanthanide metals, and actinide metals, which promote the formation of UO₂ or bimetallic U(IV)-containing oxides through a two-electron transfer process. The absence of U(IV) solid products was observed in the presence of alkali metal ions. Mechanistic studies revealed that strong binding affinities between U(IV) and certain secondary metal ions suppress the re-oxidation of U(IV) to U(VI), leading to the generation of U(IV)O₂ and MₓU(IV)O₂. This work provides fundamental insights into the electrochemical behavior of uranium in aqueous media and offers a promising approach for uranium capture from nuclear waste and contaminated water.